The present invention relates to a blood collection needle and, more specifically, to a blood collection needle to be used for collecting blood by puncturing a blood vessel of a subject with one end thereof and inserting the other end into a vacuum blood collection tube so as to communicate the interior of the blood vessel and the interior of the vacuum blood collection tube, thereby collecting blood of an amount corresponding to a negative pressure in the vacuum blood collection tube.
Hitherto, a blood collecting unit which is adapted to be able to draw blood a plurality of times with a single puncture by using a vacuum blood collection tube has been used (for example, see U.S. Pat. Nos. 5,222,502, and 5,303,713, FIG. 5). The blood collecting unit of this type includes a blood collection needle provided with a needle for puncturing a patient's skin, a needle for puncturing a rubber plug of the vacuum blood collection tube, a needle hub which can fix these needles, and a resilient tip mounted to the needle which is to be used for puncturing the vacuum blood collection tube so as to enclose the same; a blood collection tube holder which fixes the blood collection needle and fits onto the vacuum blood collection tube; and the vacuum blood collection tube sealed with the rubber plug.
For collecting blood, the blood collection needle is fixed to the blood collection tube holder first, and the vacuum blood collection tube is fitted to the blood collection tube holder, whereby the needle for puncturing the vacuum blood collection tube is exposed from the resilient tip and hence the vacuum blood collection tube is puntured, thereby starting blood collecting.
When blood collecting is carried out by the blood collecting unit, the internal pressure of the patient's blood vessel is increased by an avascularization member prior to puncture of the needle. However, when the avascularization member is released during blood collecting, the internal pressure of the blood vessel becomes lower than the internal pressure of the blood collection tube, and hence blood in the blood collection tube may flow back into the blood vessel. Since the blood collection tube is generally unsterilized and the interior thereof may be contaminated by bacteria or the blood collection tube may contain chemicals such as blood coagulation agent, damage caused by backflow of the bacteria or the chemicals into the patient with the blood is not desirable.
Such a problem can be solved at least by considering the timing to release the avascularization member. However, since the technique of blood collecting is not consistent, development of a blood collection needle which can prevent backflow of blood from the blood collection tube into the patient's blood vessel without depending on the timing of releasing the avascularization member is desired.
For example, a blood collection needle having a check valve as a mechanism that can prevent backflow of blood has been developed (for example U.S. Pat. No. 3,557,778, JP-A-53-97289, JP-A-57-11661, and JP-A-56-143144). The blood collection needle disclosed in U.S. Pat. No. 3,557,778 includes a ball valve in a needle hub, and when the internal pressure in the patient's blood vessel is lowered to a level lower than the internal pressure in the blood collection tube, the valve moves toward the needle which is inserted in the patient to clog a proximal portion of the needle, thereby preventing backflow of the blood into the patient. The blood collection needle disclosed in JP-A-56-143144 includes a tubular valve disposed in a needle hub, and backflow of blood to the patient can be prevented by the movement of the valve also caused by a pressure difference. On the other hand, the blood collection needles disclosed in JP-A-53-97289 and JP-A-57-11661 include a duckbill valve, which allows only one-way flow of blood, in a needle hub, and when backflow of blood occurs, the valve is closed according to the blood flow, and prevents the blood from flowing back into the blood vessel.
The blood collection needles using the check valve described above can prevent backflow of blood into the patient. However, although the blood collection needles provided with the ball valve or the tubular valve are adapted to cause movement or deformation by the difference between the internal pressure in the blood vessel and the pressure in the blood collection tube, there arises a temporary difference between occurrence of the pressure difference and completion of movement or deformation, and if the pressure difference is very small, the movement or the deformation may not occur, and hence there may be a case where the backflow of blood to the patient cannot be completely prevented. Also, the duckbill valve is expensive, and hence the blood collection needle provided with such a valve is increased in cost even though it is a disposable product.
Accordingly, it is an object of the present invention to provide a blood collection needle which reacts immediately to backflow of blood, is capable of preventing the backflow of blood completely even when the difference between the internal pressure in a blood vessel and the internal pressure in a vacuum blood collection tube is very small, and is kept low in cost.
After having devoted themselves to study, the inventors found that the above-described problems can be solved by a blood collection needle obtained by providing a check valve having a novel shape including a bowl portion which can trap blood which tries to flow backward and a guiding portion which makes the valve move in an adequate direction in a needle hub, and achieved the present invention.
In other words, the present invention is:
(1) a blood collection needle including: a needle tube having an edged distal end for puncturing a patient's skin; a needle tube having an edged distal end for puncturing a rubber plug which seals a blood collection tube; a hub for securing respective proximal portions of the two needle tubes and having an internal passage being capable of bringing the two needle tubes into communication with each other; a resilient cap fitted to the hub so as to embrace, in a liquid-tight manner, the distal end of the needle tube into the rubber plug; and a valve member disposed in the internal passage of the hub which allows only a blood flow from the needle tube puncturing the patient to the needle tube puncturing the rubber plug, characterized in that the valve member includes a bowl portion to be disposed so that an opening is faced toward the needle tube for puncturing the rubber plug and a guiding portion provided on a bottom surface of the bowl portion for causing the valve member to move to a predetermined position which closes the internal passage;
(2) the blood collection needle according to (1), wherein the internal passage of the hub includes a void which accommodates the bowl portion of the valve member and a guiding passage which accommodates the guiding portion of the valve member and can close the internal passage by abutting with an outer peripheral surface of the bowl portion of the valve member;
(3) the blood collection needle according to (2), wherein a portion of the guiding passage of the hub which abuts the outer peripheral surface of the bowl portion of the valve member is formed with an abutment surface having a shape corresponding to the outer peripheral surface of the bowl portion;
(4) the blood collection needle according to any one of (1) to (3), wherein the bowl portion of the valve member has a semi-spherical shape;
(5) the blood collection needle according to any one of (1) to (3), wherein the bowl portion of the valve member has a conical shape;
(6) the blood collection needle according to any one of (1) to (5), wherein the guiding portion of the valve member has a solid column shape;
(7) the blood collection needle according to any one of (1) to (5), wherein the guiding portion of the valve member has a solid conical shape;
(8) the blood collection needle according to (6) or (7), wherein the guiding portion is hollow and communicates with the opening of the bowl portion through the bottom surface of the bowl portion;
(9) the blood collection needle according to any one of (1) to (8), wherein the hub includes a vent path for allowing the internal passage and an outer atmosphere to communicate with each other, and an air permeable/blood impermeable filter fixed within the vent path in a liquid-tight manner;
(10) the blood collection needle according to any one of (1) to (9), further including a spring member which urges the valve member in a direction to close the internal passage, the spring member being disposed in the void of the hub; and
(11) the blood collection needle according to (10), wherein the spring member is clamped between the bowl portion of the valve member and a wall surface on the side of the needle tube for puncturing the rubber plug.